Degradation Phenomena of Wooden Pillars in the Main Hall of the Fengguo Monastery, Yixian, Liaoning, China - Scientific Investigation with XRD, IC, and FTIR Analysis -

Abstract

The Main Hall of the Fengguo monastery in Yixian county, Liaoning province, China, is the best preserved and largest wooden Buddhist structure, typical of the Liao dynasty style, in China. However, some degradation to the timber frame of the Main Hall has been noted, and this is causing concern in terms of the long-term preservation of the structure. In this study, wooden pillars showing the degradation phenomena of whitening, for areas in contact with the stone floor, and extensive surface damage at higher locations(mostly above 1 m) have been examined. Samples taken from wooden pillar surfaces were analyzed using X-ray powder diffraction, Fourier-transform infrared spectroscopy(FTIR), ion chromatography, and pH measurements. With respect to the whitening phenomenon, we found inorganic calcium precipitates and oxalate ions, along with higher pH values. These symptoms indicated that chemical changes were taking place in response to alkaline conditions, suggesting that alkaline mixtures with calcium content in the foundations may be responsible. Regarding the upper surface-damaged areas, no valid evidence for chemical degradation was found using FTIR analysis, while damaged areas exhibited the presence of more bat guano-related materials than which were apparent in undamaged areas. The occurrence of this surface-damaged phenomenon has therefore been attributed to physical damage caused by bat activity over long periods of time.